Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

Annotations already declare readOnlyHint=true, so the safety profile is covered. The description adds contextual behavior beyond that: it explains that the athlete's saved workouts are deliberately not in the catalog map and enumerates the returned fields (id, title, zone, duration, TSS, IF, source).

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Is the description appropriately sized, front-loaded, and free of redundancy?

Three sentences, front-loaded with scope and followed by usage guidance and output details. The middle sentence is a bit long and repeats the point about saved workouts, but every sentence contributes useful information.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

For a read-only search tool, the description covers the search scope, when to use it, filtering options, return fields, and downstream integration via plan_workouts. There is no output schema, but the return fields are explicitly listed. No critical calling detail is missing.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Schema description coverage is 83%, so the baseline is 3. The description maps 'sport, target zone, and a duration window' to the relevant schema parameters, but adds little beyond what the schema already states for those fields. Query and limit are not described in prose, though the schema covers them well.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Does the description clearly state what the tool does and how it differs from similar tools?

The description opens with a specific verb ('Search') and names three distinct resources: the Blocks catalog, coach collections, and the athlete's saved workouts. It distinguishes itself from siblings by noting the 'mine' source and by saying returned ids can be passed to plan_workouts.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Does the description explain when to use this tool, when not to, or what alternatives exist?

It explicitly tells the agent to reuse an existing workout before inventing one, and positions this tool as the mechanism for that lookup. It gives concrete search angles (keyword, rep interior, saved workouts) but does not name alternative search tools or state exclusion conditions.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.